The present invention is generally related to a portable telephone apparatus, and more particularly to a cellular portable radiotelephone utilizing a movable housing element to permit the user to answer and terminate telephone calls and control various radiotelephone functions by opening or closing the movable element. This invention is related to that disclosed and claimed in U.S. patent application Ser. No. 439,983 filed on Nov. 20, 1989 and assigned to the assignee of the present invention.
Telephones having a rotary or pushbutton dial mechanism and other buttons integral to the handset portion have become commonplace in landline subscriber telephone instruments. This integral arrangement offers the telephone user the convenience of bringing the user interface mechanism and control buttons close to the user.
Radiotelephone operation, such as that offered in cellular radiotelephone or in cordless telephone sets, provide a mobility to the telephone user which landline telephone does not provide. The absence of a cord and the small size of the portable radiotelephone unit enables the user to carry the unit essentially wherever the user goes. Recent innovations have enabled voice recognition circuitry to be used with portable radiotelephones in order to provide the user the ability to dial and control the operation of a portable radiotelephone with the spoken voice. Undesired operation of voice recognition circuitry in a radiotelephone setting, however, may turn the equipment on or off, cause transmission of unwanted signals and prevent use of a radio channel, or cause undesired functions to occur. Such undesired activation of voice recognition is likely to engage functions which reduce the operating life of the battery which powers the portable radiotelephone.
Additional drain upon the battery of the radiotelephone is made by the apparatus providing illumination for the dial keypad and number display. Previously, in order to activate the portable telephone's display or backlighting, the user would have to press a button which would initiate a function, digit, etc. The user would then have to press a clear button to delete this function or digit. Such an operation provides an unwanted opportunity for error and may, for example, have enabled the user to inadvertently erase the contents of the scratch pad memory used for dialing a call. A user, having experienced an undesired operation caused by an inappropriate press of a clear button, quickly becomes discouraged from using the otherwise useful illumination feature.